Superconductivity

What is it?  Helium is the noblest of the noble gases.  It is incredibly inert, meaning that it almost never reacts with other elements.  At room temperature, helium atoms are paired with each other to form the gas He₂.  Helium has two protons and two electrons.  Virtually all helium on earth has two neutrons, while every millionth or so helium atom only has one.

Why should I care?   Most known for use in lighter than air balloons, helium is more often used for medical and industrial purposes.  Helium, which becomes liquid at the astoundingly low temperature of 4.2K (−269°C or −452°F), is used as a cryogen (a cooling medium) for superconducting magnets in MRI machines, research magnets, and large particle accelerators such as the new Large Hadron Collider at the CERN research center in Switzerland.  Helium is the only element with a boiling point low enough to act as a cryogen for these so-called low-temperature superconductors.  Helium is also used in arc welding and as a protective gas when growing silicon and germanium crystals.

Where does it come from?   The earth’s supply of helium comes from the nuclear decay of radioactive materials, which is ongoing.  When substances such as Uranium decay, they release beta particles (helium).  Most helium makes its way through the earth’s crust, and floats up out of the earth’s atmosphere.  Some, however, is trapped in pockets with natural gas.